1. Field of the Invention
The invention relates to electronic devices and in particular, to those employing digital-to-analog conversion circuitry.
2. Description of Related Art
Modern electronic systems are typically realized as a complete "system on a chip." Such systems typically integrate analog and digital functionality onto the die of a single integrated circuit. Such systems offer lower cost, power, and size benefits to the customer.
Often a system will be based on a digital signal processing (DSP) core that implements system functionality through the use of discrete mathematical algorithms that are realized through hardware, firmware, or programmable means. In order for the system to interface to analog based continuous signals, such systems typically employ the use of a digital-to-analog converter (DAC). Examples of such systems include direct digital synthesis (DDS) products, TDMA/CDMA wireless communication systems, as well as audio and video devices.
CMOS continues to be the dominant process used to fabricate integrated circuits that contain such systems-on-a-chip. Driven by the desire for further miniaturization, advances in CMOS fabrication processes continue to lead to integrated circuits with lower and lower operating voltage and power specifications. While digital circuit designs can readily be transported to a more advanced process, analog circuit designs often produce poorer results when transported, or cannot be transported at all.
Traditional circuit designs for digital-to-analog converters suffer in this respect and generally perform poorly when moved to advanced CMOS fabrication processes. Consequently, there is a need in the art for a digital-to-analog converter providing both good AC and DC performance characteristics, and occupying minimal die space, when implemented using advanced integrated circuit fabrication processes.